Centralized traffic controlling system for railroads



Nov. 2, 1937. w. T. POWELL 2,097,801

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed Sept. 1, 1936 Patented Nov. 2, 1937 UNITED STATES OENTRALIZED- TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Winfred T. Powell, Rochester, Y., assignor. to I(general Railway Signal Company, Rochester,

Application September 1, 1936, Serial N0. 98,906

1 Claim.

This invention relates to railway centralized traffic control systems and more particularly to a communication means for such a system, whereby information may be transmitted to a remote 5 point concerning the presence or absence of trains in a plurality of track sections over a mimimum number of line circuits.

In centralized traffic control systems it is expedient to employ a minimum number of line 0 wires extending from the control point to various distant locations, both because of the cost of line wire as well as the increased cost of maintenance of a larger number of wires over the considerable distances necessary to extend such circuits. It is found expedient in such systems tonot only provide means for transferring information to the control point concerning the operated positions of the various devices, such as signals and switches, but also to transmit information concerning the presence or absence of trains in various track sections and consequently in systerns requiring this information from anumber of track sections considerable savings may be made by multiplying the use of the linecircuits employed to transmit this information.

In View of the above and other considerations it is proposed to provide means for communicating information to a distant pointregarding the presence or absence of trains in two adjacent track sections and to accomplish this transmission over a single line circuit.

Other objects, purposes and characteristic features of this invention will be in part apparent and in part obvious as the description of the in:

vention progresses, during which reference will be made to the accompanying drawing which shows in a diagrammatic and conventional manner two systems for indicating at a distant point the condition of two adjacent track sections in accordance with this invention. In the draw- Fig. 1 diagrammatically illustrates one form of the invention. v

Fig. 2 is a fragmentary view of a second form of the invention.

, Referring to Fig. 1-, the invention has been shown applied to a track layout A, comprising a stretch of main track and a turnout track which is connected to themain track by a switch TS.

' The section oftrack approaching the switch TS is shown divided into two adjacent track sections I and 2, with the respective track relays IT and 2T arranged in a conventional manner to detect the presence of trains therein.

In the dispatchers ofiice, or the control point,

a miniature track diagram TD' is provided, which diagrammatically illustrates the distant track layout 'A. The track diagram contains two miniature incandescent lamps or indicators ITI and ZTI, which are arranged therein at positionsso that they may be readily associated with the corresponding track sections I and 2.

Referring to the form of the invention shown in Fig. 1, the apparatus associated with the miniature track diagram TD includes in series a three- 10 position polar line relay F and a neutral line relay MG. Relay F is designed so that its polar contact 3 will operate to either its right or left hand position when the line is weakly energized, but the neutral contact of relay MG will pick up 15 only when the line is strongly energized. A polarized source of energy is shown at the track location as a split battery B and: the symbols and are used. tdindicate opposite terminals of a local source of energy at the control oifice, which 20 source has not been shown.

In describing'the invention it will be considered that a train, approaching track layout A from the left, enters track section I thereby dropping the associated track relay IT. Energy is now supplied over a normally deenergized line circuit to relays F and MG at thedispatchers ofiice through a circuit that may be traced from the positive terminal of battery B, back contact 5 of relay IT, front contact 6 of relay 2T, resistance R, back contact 1 of relay IT, line wire L, the winding of relay MG, the winding of relay F, common wire COM, to the mid terminal Cyof battery B. The inclusion of resistance R in the line circuit just traced results in a relatively low positive energization of the line, that is, the energy flows from right to left through the windings of relays F and MG, with the result that relay F will be operated to close contact 3 to its left hand position and relay MG will not be. 4

picked up. An indication of the occupancy of section I isthen displayed on the miniature track diagram by the energizat'ion of lamp' ITI through an obvious circuit that is closed at contact 3 of relay F in its left-hand position. 4'

When the train in section I progresses to a point in which it is occupying section 2 as well as section I, it is obvious that both track relays IT and 2T will be dropped with the result that resistance R will be short-'circuited and a rela- 5O tively high degree of positivelenergization'will' be applied to line L which will maintain relay E positioned tothe left for lighting lamp ITI and relay MG will be picked up for lighting lamp 2TI. This circuit may be traced from the positive 55 terminal of battery B, back contact 5 of relay IT, back contact 8 of relay 2T, line wire L, the winding of relay MG, the winding of relay F, common wire COM, to mid terminal C of battery B. The indicators ITI and 2T1 are energized through obvious circuits that are closed at contact 3 of relay F in its left-hand position and front contact 4 of relay MG respectively.

When the train leaves the track section with which relay IT is associated, the picking up of this relay, with relay 2T down, will remove the short-circuit from resistance R and energize the line with a low degree of negative current, that is, the current will flow through the windings of relays MG and F in a direction from left to right. Relay MG now releases its armature and contact 3 of relay F is positioned to the right for extinguishing lamp ITI and maintaining lamp 2TI lighted. This circuit may be traced from the negative terminal of battery B, front contact I of relay IT, resistance R, back contact 6 of relay 2T, line wire L, windings of relays MG and F, common wire COM, to mid-terminal C of battery B. Indication lamp 2T1 is now lighted through a circuit that includes contact 3 of relay F in its right-hand position.

When the train leaves the section with which relay 2T is associated, the picking up of this relay places the line circuit in its normal deenergized condition and lamps ITI and 2TI at the control ofiice are extinguished.

Inasmuch as the operation of the present system is not entirely symmetrical for traffic in either direction, it will now be considered that section 2T only is occupied bya train progressing from right to left over track layout A.

A train entering from the right and dropping relay 2T energizes the line with a low degree of negative current which positions relay F to the right for lighting lamp 2T1 and. relay MG does not pick up under this condition; and when the cause both relays IT and 2T are down.

train progresses to a point in which it occupies section ,I and section 2 the dropping of relay IT changes the line circuit from a low negative energization to a high positive energization be- This positions relay F to the left and picks up relay MG for lighting both lamps ITI and Z'I'I all in a manner previously described.

This sequence of operation is different from that previously described inasmuch as, in the first case, the polarity on relays F and MG was not changed when the train moved from section I to a point where it occupied section 2 as well as section I.

When the train leaves section 2 track relay 2T. picks up and under this condition the line is energized with a low degree of positive current which causes relay MG to release its armature and positions relay F to the left for lighting lamp ITI (and for extinguishing lamp 2T1), through the circuit previously described for a train moving into section I from the left.

When this train leaves the section with which relay IT is associated, both relays IT and 2T will be picked up for deenergizing the line circuit wh ch is its normal condition.

Referring to Fig. 2, there is here shown a modified circuit arrangement for energizing the indication lamps ITI and ZTI at the control point, in which a relay F is employed, having a neutral contact 9 and a three position polar contact 3 This relay F is so designed that contacts 3 and I] operate in a manner similar to contacts 3 and 4 of relays F and MG, in Fig. 1, therefore, only one'relay is required at the control office for energizing the lamps ITI and 2TI it being understood that the apparatus at track layout A functions as previously described.

In other words, the structure and winding of relay F are so proportioned with respect to the voltage of battery B, the resistance of R and the line resistance that a low degree of line energization efiects the actuation of contact 3 and not contact 9, while a high degree of line energization efiects the actuation of both contacts 3 and 9. In brief, relay F is of the marginal type with respect to the operation of its contact 9, and of the sensitive type with respect to the operation of its contact 3 Communicating means for a railway trafiic control system have thus been provided, in which information as to the occupied or unoccupied condition of either one or both of two track sections may be transmitted to a remote point over a single polarized line circuit without the employment of alternating current or the like. The track sections to be indicated need not be adjacent as shown herein, but in most cases, the apparatus along the trackway is so grouped that it is expedient to indicate adjacent sections over the same line circuit.

The above rather specific description of one form of the present invention is given solely by way of example and is not intended in any manner whatsoever in a limiting sense. It is also understood that various modifications, adaptations and alterations may be applied to meet the requirements of practice without in any manner departing from the spirit or scope of the present invention except as limited by the appended claim. 7

What I claim is:

In a system for indicating traific conditions, a normally deenergized line circuit connecting a central ofilce and two distant track sections each provided with a track relay, a three position polar relay included in series in said line circuit at said office and responsive to the polarity of energization of said line circuit whenever it is energized, a marginal relay at said ofiice included in series in said line circuit and responsive to a relatively high degree of energization and unresponsive to a relatively low degree of energization, a source of energy and a resistor associated with said distant track sections, circuit means including contacts of said track relays for connecting said source and said resistor in series to supply said line circuit with energy of said low degree of one polarity or the other in accordance with the dropped away condition of one or the other of said track relays or to supply said line circuit with energy of said high degree of said one polarity when both said track relays are dropped away, two indicators in said ofiice, and circuit means including contacts of said polar and marginal relays for energizing one or the other of said indicators when said line circuit is energized to said relatively low degree with said one or said other polarity and for energizing both said indicators when said line circuit is energized to said relatively high degree.

WINFRED T. POWELL. 

